Solved: PC Restarts When I Go Online / Turn Modem On, Please Help!!

My pc's in sh*t street, I'm only able to get online using Safe Mode with Networking, If i try accesing the internet any other way ie as soon as i turn my cable modem on the pc just restarts...

I've tried system restore and for some reason there's not any restore points any more so that option's out the window, Also tried the virus deleter 'Stinger' which has worked in the past but that's not sorted it, I'm normally ok at sorting things like this out but this time it's all been in vain...

Before someone mentions it, I honestly don't surf porn sites as the computer's in the kitchen and my house is pretty busy so i thought i'd clear that one up ...

Does Anyone Know A Solution?.

Thanks In Advance For Any Help

P.S - Sorry if i've posted this in a wrong section only it's the first time i've ever used the site

Double click on the HJTsetup.exe icon on your desktop.
By default it will install to C:\Program Files\Hijack This.
Continue to click Next in the setup dialogue boxes until you get to the Select Addition Tasks dialogue.
Put a check by Create a desktop icon then click Next again.
Continue to follow the rest of the prompts from there.
At the final dialogue box click Finish and it will launch Hijack This.
Click on the Do a system scan and save a log file button. It will scan and then ask you to save the log.
Click Save to save the log file and then the log will open in notepad.
Click on "Edit > Select All" then click on "Edit > Copy" to copy the entire contents of the log.
Come back here to this thread and Paste the log in your next reply.DO NOT have Hijack This fix anything yet. Most of what it finds will be harmless or even required.

You need to go here and install "Service Pack 1" This will patch numerous security holes in IE and Windows. As your machine stands now it is wide open to attack from all sorts of nasties. You need to get these updates before we proceed or we will be wasting our time.

DO NOT install Service pack 2 yet. If you install SP 2 on an infected machine it will cause serious problems. Just get Service Pack 1 installed. After you get SP1 installed, restart your computer.

I think i'll have a fresh start and format it again, I'll need to keep an eye on how it's run in future as i'm not home that much and my brother who i'd say has let most of this happen will need to learn a few things...

My friend re-formatted this machine a few years back and formatting is something i've never done so could you please direct to the most helpful thread on here on how to do it...

Also, will my service tag still be valid?, I bought the machine in 2002, I still have all the original Windows drivers etc....

After you format and reload make sure to put the anti-virus software on and get the windows updates all the way to SP2. Also turn on automatic updates so your brother does not have to remember to do them!